[fix] make names non-nullable

[serenajiang]

CATEGORY

Choose one

• Bug Fix
• Enhancement (new features, refinement)
• Refactor
• Add tests
• Build / Development Environment
• Documentation

SUMMARY

If a user somehow creates a table with a null name, 503 errors occur whenever repr(table) is called because __repr__ returns a non-string type.

Fixed schema to make columns referenced by __repr__ non-nullable.

Before running the migration, you must manually fix any records with null clusters.cluster_name, dbs.database_name, or tables.table_name. To find problematic records, run a query like:

SELECT 
    *
FROM 
   tables
WHERE 
   table_name IS NULL

TEST PLAN

Confirmed that after upgrade, I get a warning if I try to insert a row with a null table_name.

Confirmed that after downgrade, I am able to insert a row with a null table_name with no problem.

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

REVIEWERS

@graceguo-supercat @etr2460 @john-bodley

[john-bodley]

@serenajiang would you mind adding the Alembic migration to the PR?

[codecov-io]

Codecov Report

Merging #8332 into master will increase coverage by 5.52%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #8332      +/-   ##
==========================================
+ Coverage    67.7%   73.22%   +5.52%     
==========================================
  Files         447      115     -332     
  Lines       22652    12404   -10248     
  Branches     2363        0    -2363     
==========================================
- Hits        15336     9083    -6253     
+ Misses       7178     3321    -3857     
+ Partials      138        0     -138

Impacted Files	Coverage Δ
superset/connectors/druid/models.py	82.41% <100%> (ø)	⬆️
superset/connectors/sqla/models.py	84.96% <100%> (ø)	⬆️
superset/models/core.py	81.29% <100%> (-0.64%)	⬇️
superset/db_engine_specs/mysql.py	43.13% <0%> (-49.02%)	⬇️
superset/db_engine_specs/sqlite.py	54.83% <0%> (-16.13%)	⬇️
superset/dataframe.py	92.12% <0%> (-2.37%)	⬇️
superset/db_engine_specs/base.py	84.38% <0%> (-1%)	⬇️
superset/views/core.py	69.95% <0%> (-0.21%)	⬇️
superset/utils/core.py	88.41% <0%> (-0.17%)	⬇️
... and 332 more

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[john-bodley]

Please remove this as the migration should fail if there are NULL values. Instead please add a line item to UPDATING.md to indicate that this migration may fail (see other examples).

[john-bodley]

Please use the generic SQLAlchemy types as used in other migrations.

[etr2460]

nit: no newline

[etr2460]

One other request, can you add sql snippets to the PR explaining how to find the bad rows if the migration fails? you can follow the format here as an example: #5451